Emulsifier/detergent compounds for metalworking lubricants

ABSTRACT

Metal sulfonate emulsifier and detergent compounds for use with various metalworking lubricants are taught together with the method of preparing same. The sulfonates are prepared by co-sulfonating selected alkylbenzenes and certain oils with oleum. More specifically, the method involves preparation of a complex mixture of alkylbenzenes and lubricating oils, sulfonation by means of oleum only, and conversion to a metal sulfonate via specific processing steps.

RELATED APPLICATIONS

This patent application is claiming the benefit of the U.S. ProvisionalApplication No. 60/508760, filed Oct. 3, 2003, and entitledEmulsifier/Detergent Compounds for Metalworking Lubricants.

FIELD OF THE INVENTION

The subject invention relates generally to metalworking lubricantadditives, and more specifically to improved emulsifier and detergentcompositions prepared by co-sulfonating selected alkylbenzenes and oilswith oleum.

BACKGROUND OF THE INVENTION

Metalworking continues to be a major industry throughout the world.During a metalworking operation, the metal in question may be forged,rolled, stamped, cut, formed or ground. Almost all metal objects fromthe smallest screws to large beams have been processed with at least onemetalworking operation.

Successful metalworking requires the use of good fluids which canfunction both as a lubricant and a coolant. These lubricants andcoolants are derived from a number of different types of metalworkingfluids. Included are fatty acid soaps, formulated hydrocarbons,emulsified oils and aqueous solutions. These various products are usedto manufacture products ranging from the drawing of wire to the toppingof nut threads. For each manufacturing job, the metalworking fluid mustbe chosen to meet the demands of a specific application.

There are four major types of fluids used in today's metalworkingindustry. These products include:

Straight Oils

Soluble Oils

Chemical Solutions

Semichemical Solutions

This invention concerns the formation of emulsifiers or detergents whichimpart superior quality to soluble oils and straight oils used in themetalworking industry.

Soluble oils are actually oil-in-water emulsions that take advantage ofthe lubricity of oils and also the cooling properties of water, while atthe same time provide corrosion protection. Soluble oils are thedominant type of water base metalworking fluid. The use of thesematerials instead of neat hydrocarbon based metal working fluids allowsmanufacturers to increase their production rate without sacrifices insurface finish, tool life, or die life. They also are cleaner than oilbased formulations with reduced smoke or fumes at a much lower firehazard. Soluble oils are also very versatile due to their composition.The required lubrication and cooling properties of soluble oilmetalworking fluids can be adjusted simply by modifying the dilutionratio or changing the type or amount of lubricity additives.

Another advantage of soluble oils when compared to neat hydrocarbonbased metalworking fluids is the cost. The formulated soluble oilconcentrate normally costs more than a neat hydrocarbon formulated oil,however, the cost is significantly reduced because the concentrate canbe diluted many times with significant volumes of water.

Because of these many benefits, approximately ninety percent (90%) ofall metal removal operations use water based metalworking fluids. Thesubject invention provides a novel and superior emulsifying agent forsuch fluids.

Once again, it must be pointed out that the stability of the oil inwater emulsion is the key to the success of the soluble oil formulation.The purpose of this invention is to prepare chemical agents that willprovide this much needed emulsion stability.

Soluble oil metalworking fluids are well accepted by the metalworkingindustry and the presence of a hydrocarbon oil provides many operatorsand machinists with a significant degree of comfort and protection fromunknown diluents. The soluble oil fluid is first made as a concentrate.The concentrate is then diluted with water by the industrial consumer inhis own shop. The concentrate is supplied by a number of differentcompanies throughout the world and a typical soluble oil concentrate isshown below: TYPICAL SOLUBLE OIL CONCENTRATE FORMULATION COMPONENT % BYWEIGHT Mineral oil 70-85 Emulsifier* 10-20 Coupling agents 1-5 Corrosioninhibitors  5-10 EP additives  0-10 Biocide trace Water 0-5*The subject of this patent

The emulsifier described in this patent can also be used with syntheticoils or fluids to provide a hydrocarbon free formulation. For example,synthetic esters derived from pentaerythritol and C₁₂ to C₁₈ fatty acidscan be used to replace the mineral oil shown in the above concentrateformulation. This synthetic formulation can then be used as a solubleoil in rolling compounds for steel.

It has been the goal for a number of years in the metalworking industryto replace chlorinated and active sulfur compounds in soluble oilformulations. Chlorine is classified as a hazard and is very difficultand costly to dispose of. Active sulfurized materials can promote thegrowth of bacteria in active metalworking fluids. The emulsifierdescribed in this patent can be used to emulsify polymeric esters usedin soluble oil formulations as lubricity agents. This enables theformulator to eliminate the chlorine and sulfur in many applications.

There are other performance advantages of the emulsifiers describedherein. The sulfonate mixtures disclosed increase both lubricity andcorrosion protection. Sulfonates are anionic surfactants which bear anegatively charged ion, which makes up the hydrophilic portion of themolecule. This property can be exploited to provide another advantage ofthe subject emulsifier. When the soluble oil-water mixture has come tothe end of its useful life, the mixture can be treated with acid andalum or a polyelectrolyte to neutralize the charge and thereby eliminatethe emulsifying property of the sulfonate. The oil portion of themetalworking fluid then separates out and can be readily removed. Thisfactor is important for essentially eliminating disposal problems ofsoluble oil fluid.

The subject compositions can also be used successfully in metalworkingformulations known as straight oils. These products are primarilyderived from petroleum fractions containing metal working additives.Synthetic base stocks can also be used in the straight oil formulations.Straight oil metal working fluids contain no water and are sold ready touse. They are excellent lubricants but have limited cooling capacities.

Formulations containing the products of this invention are shown below:TYPICAL STRAIGHT OIL FORMULATION COMPONENT Parts BY WEIGHT Diluent Oil60-90 Metal Sulfonates*  5-20 EP additives  5-20 Lubricity additives 0-10 Antioxidents 0-4*The subject of this patent

It should be pointed out that the diluent oils can be paraffinic,naphthenic or synthetic and that the metal sulfonate can be derived fromlithium, sodium, potassium or calcium, or mixtures thereof.

Straight oil metalworking lubricants continue to be the products ofchoice in many metalworking operations. They are important inapplications requiring drawing and forming on low speed, high severitymetal removal. The metal sulfonates compositions of the subjectinvention perform well in these applications. The major advantages ofusing these lubricants are low staining and clean burn offcharacteristics.

OBJECTS AND ADVANTAGES

The highlights, advantages and benefits of the subject invention areoutlined as follows:

1. The sulfonate emulsifier and/or detergent composition contains a verywide range of molecular weights.

2. The molecular weights of the constituents of these sulfonateemulsifiers and/or detergent composition range from about 350 to over650.

3. The composition contains a wide range of different molecularstructures.

4. The composition of the emulsifier or detergent varies from acompletely water-soluble sulfonate to a completely oil solublesulfonate.

5. The composition exhibits superior emulsifying properties similar tothe so-called natural sulfonates derived from lubricating oils.

6. The invention provides excellent stable emulsions.

7. The emulsifier or detergent of invention is compatible with naturaloils, synthetic oils and white oils.

8. The color is consistently low and better than the natural sulfonateemulsifiers and better than most synthetic detergents.

9. The viscosity is consistently low and better than the naturalsulfonate emulsifiers and most synthetic detergents.

10. The processing of the invention provides a more pure sulfonateemulsifier or detergent with a very low inorganic salt content.

11. The composition of the invention exhibits excellent rust prevention.

There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofthat follows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described hereinafterand which will form the subject matter of the claims appended hereto. Inthis respect, before explaining at least one embodiment of the inventionin detail, it is to be understood that the invention is not limited inits application to the details of construction and to the arrangementsof the components set forth in the following description or illustratedin the drawings. The invention is capable of other embodiments and ofbeing practiced and carried out in various ways. Also, it is to beunderstood that the phraseology and terminology employed herein are forthe purpose of description and should not be regarded as limiting. Assuch, those skilled in the art will appreciate that the conception, uponwhich this disclosure is based, may readily be utilized as a basis forthe designing of other structures, methods and systems for carrying outthe several purposes of the present invention. It is important,therefore, that the claims be regarded as including such equivalentconstructions insofar as they do not depart from the spirit and scope ofthe present invention.

Further, the purpose of the foregoing abstract is to enable the U.S.Patent and Trademark Office and the public generally, and especially thescientists, engineers and practitioners in the art who are not familiarwith patent or legal terms or phraseology, to determine quickly from acursory inspection the nature and essence of the technical disclosure ofthe application. The abstract is neither intended to define theinvention of the application, which is measured by the claims, nor is itintended to be limiting as to the scope of the invention in any way.

DETAILED DESCRIPTION OF THE INVENTION

The subject invention is prepared by oleum sulfonation of a mixture oflubricating oil and alkylbenzenes. These raw materials are selected fromthe following materials:

1. Solvent dewaxed heavy paraffinic oils with the following typicalproperties:

-   -   Specific gravity=0.88    -   Viscosity Index=95    -   IBP (approximately)=335° C.    -   Pour Point=−6° C.    -   Flash, COC=246° C.    -   Viscosity @ 40°=109-117 cSt    -   Suitable oils for this portion of the invention include Exxon        Mobil's neutral petroleum lubricating oils designated as 600        Solvent Neutral and America's Core 600. It must be emphasized        that the invention requires the use of two different lubricating        oils. The other lubricating oil is lower in molecular weight and        shown below.

2. Solvent dewaxed paraffinic oils which are lower in molecular weightand lighter oils than the materials shown above. These products have thefollowing typical properties:

-   -   Specific gravity=0.88    -   Viscosity at 100° C.=11.4 cSt    -   Boiling point=330-600° C.    -   Viscosity Index=90=95    -   Flash, COC=238° C.

3. Linear mono alkylbenzenes containing alkyl side chains of 10-14carbon atoms. These products are used for the preparation ofbiodegradable detergents. The molecular weight is especially suitablefor the manufacture of liquid detergents. Some typical propertiesinclude:

-   -   Molecular weight=233-237    -   Density @ 15° C.=0.85-0.87    -   Bromine number=10 max.    -   Saybold color=29 min.    -   % Tetralins=0.5% max.    -   Initial Boiling Point=275° C.    -   Viscosity @ 20° C.=5-10 cps    -   Suitable products include Petrelab 500Q manufactured by Petresa        Inc., and SASOL N-501 manufactured by Sasol Inc.

4. Heavy alkylbenzenes, primarily containing dialkylbenzene mixtures orderivatives of C₁₀-C₁₄ carbon alkylbenzene fractionation bottoms. Thesedialkylbenzenes are composed of unbranched groups. Typical propertiesinclude the following:

-   -   Molecular Weight=350-370    -   Density @ 15° C.=8.3-8.5    -   Viscosity @ 37.8° C.=12-30 cps    -   Specific Gravity=0.87    -   Flash Point Pensky Martens=181° C. min.    -   Suitable products include Vista 9050 manufactured by Sasol Co.

5. Linear Dialkylbenzenes, primarily containing dialkylbenzene mixturesderived from C₁₀-C₁₃ alkylbenzenes. The dialkylbenzenes in this alkylateare highly methyl group branched at the C-1 position. These materialsare the fractionated bottoms. Typical properties include the following:

-   -   Molecular Weight=395-405    -   Initial boiling point=685° F.    -   Viscosity @ 40° C.=22.0 cSt    -   Specific gravity=0.89

The mixture of the above five components are essential and critical tothe performance of this invention. The mixture of naturally derivedsulfonates from the two different lubricating oils plus the specialblend of different synthetic sulfonates result in an excellentemulsifier. It also must be emphasized that the difference in thestructure between the two dialkylbenzenes is essential and an unexpectedfinding. In addition, the invention requires the use of two lubricatingoils with different molecular weights.

There are allowable operating ranges for each of the components listedabove which will allow the invention to perform satisfactorily as anemulsifier or detergent. These ranges are as follows: % SUITABLE RANGEBY WEIGHT Minimum Maximum 1. Heavy Paraffinic Oil 7 25 2. LightParaffinic Oil 7 25 3. Linear Monoalkylbenzene 12 30 4. UnbranchedDialkylbenzene 25 45 5. C-1 Methyl Branched 7 18    Dialkylbenzene

Not only is the above complex mixture required for this invention, butthe conversion to the emulsifier or detergent requires specificconditions. As pointed out above, the complex mixture is converted tothe sulfonate composition by first sulfonating the mixture with oleumand then converting the resulting sulfonic acid mixture to the metalsulfonate. It is important to the invention to sulfonate the mixturewith oleum. This is in contrast to the current and most commonindustrial sulfonation procedure using gaseous sulfur trioxide. Themajority of commercial oleum sulfonation has been replaced by the sulfurtrioxide technique.

Thus the critical invention properties require:

1. A complex mixture of alkylbenzenes and lubricating oils;

2. Sulfonation by means of oleum only; and

3. Conversion to a metal sulfonate via specific processing steps.

The sulfonation procedure is outlined in the following steps:

Sulfonation

Outline of Method—Twenty percent (20%) oleum is reacted with thealkylate/oil mixture at a controlled rate and temperature. The reactionmass is then diluted with a paraffinic volatile solvent (selected fromthe group consisting of hexane, isohexane, heptane, isoheptane, octane,isooctane and others with an IBP of 250° F. or less), in this caseheptane, and allowed to settle. The spent sulfuric acid settles to thebottom and can easily be removed from the heptane/product layer.

Procedure—A known and measured amount of alkylate/oil mixture selectedfrom the ranges shown below, is charged to a suitable vessel: % SUITABLERANGE BY WEIGHT Minimum Maximum 1. Heavy Paraffinic Oil 7 25 2. LightParaffinic Oil 7 25 3. Linear Monoalkylbenzene 12 30 4. UnbranchedDialkylbenzene 25 45 5. C-1 Methyl Branched 7 18    Dialkylbenzene

Suitable mixing of the alkylate is begun and 20 percent (20%) oleum(104.5% H₂ SO₄) is slowly added to the alkylate/oil mixture.Approximately 0.5 volumes of oleum is added based upon the total volumeof alkylate/oil. The oleum addition rate should be controlled so thatthe temperature reaches, but does not exceed, 70° C. Then postmix thesulfonation mass for at least 15 minutes after the oleum addition hasbeen completed.

Continue mixing and when the mixture reaches or is cooled to 45° C.,approximately three volumes of heptane is added based upon the alkylateoil mixture. An example of the charge amounts for this procedureoutlined above is as follows: Amount, gallons Alkylate/oil mixture 4,000 20% Oleum  2,000 Heptane 12,000 Total 18,000

The above product is analyzed and then converted to a metal sulfonateemulsifier or detergent as follows:

EXAMPLE Sodium Sulfonate

Outline of Method—The heptane sulfonic acid from the above procedure isneutralized with sodium hydroxide. The neutralized reaction mass issettled and the brine layer is removed. The neutral sodium sulfonatesolution is then heated and the heptane is removed via distillation.This procedure yields a product of this invention, a sodium sulfonate.

Procedure—A known, measured and analyzed amount of heptane sulfonic acidsolution is charged to a suitable vessel. Mixing is begun and waterand/or methanol is added to the sulfonic acid mixture. The amount ofwater required is approximately five percent (5%) based upon the weightof the heptane sulfonic acid charged. Mixing is continued for 15 minutesafter the water addition and, then the acid is neutralized with sodiumhydroxide/water solution. The concentration of the sodium hydroxidesolution is not critical and concentrations up to 50 percent (50%)sodium hydroxide can be utilized. The amount of sodium hydroxide used isbased upon the analysis and amount of the heptane sulfonic acid mixture.After mixing for 30 minutes, the mixture is re-analyzed after the sodiumhydroxide solution has been added to make sure that the mixture isneutral. It is important to note that the temperature during water orsodium hydroxide solution addition must not exceed 130° F. Thetemperature must be controlled by the rates of addition. After therequired neutralization, mixing is continued for at least 30 minutes.The mixing is then discontinued and the neutral sodium sulfonate mixtureis allowed to settle for at least 12 hours. Following the requiredsettling time, the brine layer has settled to the bottom of the tank,and the brine can be removed by decantation. The heptane organic layeris then transferred to a vessel suitable for solvent removal. Heatingand mixing is begun, and the volatiles are removed via distillation. Oilcan be added at this point in the process if the analysis reveals thatan adjustment is required. Heating and mixing is continued to a bottomstemperature of 225° F. and, at this temperature, stripping with nitrogengas is begun. When the product reaches 300° F., stripping is continueduntil the material reaches an acceptable flash point. The product willhave the following typical properties: PROPERTY % BY WEIGHT % SodiumSulfonate   62-64% Flash, COC, ° F. 350-400 Viscosity, SUS @ 100° F.280-400 % Water   0.1-2.0% ASTM Color 2-4 Specific Gravity, 60° F.0.97-0.99 % Sediment trace Molecular Weight 430-475

Examples of this invention have been selected and shown below and werederived from the following raw materials: Example 1 Example 2 P-500 Q %Linear Monoalkybenzene 25 17 P-900 Q % Unbranched dialkylbenzene 41 31V-9050 % C-1 Methyl branched dialkylbenzene 14 12 600 % Heavy ParaffinicOil 10 20 500 % Light Paraffinic Oil 10 20

These raw material mixtures of alkylates and oil were then sulfonatedand converted to the corresponding sodium sulfonate using the proceduresoutlined above. The sodium sulfonates or final product mixture of sodiumsulfonate and oil had the following analysis: Example 1 Test MethodExample 2 % Sodium Sulfonate 62.1 T1409A 62.0 Molecular Weight 445AT1442 465 Flash, COC, ° F. 350 ASTM-D92 350 Viscosity, SUS @ 100° F. 64ASTM-D445 47 % Water <0.5 ASTM-D95 <0.5 ASTM Color (dilute) <4.5ASTM-D1500 3.0 Specific Gravity 0.966 T1406 0.975

These products of this invention were then tested for emulsionstabilization in hard and soft water. The products performed better thanall existing commercial products in these tests. The stability in hardwater was carried out in water containing 500 ppm calcium. Both example1 and example 2 gave excellent, stable emulsions which exceeded theperformance other commercially available sulfonate emulsifiers.

Although the present invention has been described with reference to theparticular embodiments herein set forth, it is understood that thepresent disclosure has been made only by way of example and thatnumerous changes in details of construction may be resorted to withoutdeparting from the spirit and scope of the invention. Thus, the scope ofthe invention should not be limited by the foregoing specifications, butrather only by the scope of the claims appended hereto.

1. A process for preparing a metal sulfonate useful as an emulsifier ordetergent in metalworking liquids, wherein said metal sulfonate isselected from the group consisting of lithium, sodium, potassium,calcium or mixtures thereof, said method comprising: A. Forming anadmixture consisting essentially of linear monoalkylbenzenes, unbrancheddialkylbenzenes, c-1 methyl branched dialkylbenzenes, at least twodifferent paraffinic oils and a volatile paraffinic solvent; B.Sulfonating said admixture with 20 percent (20%) oleum at mole ratios ofabout 1.1 mole to 1.4 mole of oleum per mole of aromatic compound attemperatures 70° C. or below; C. Separating the spent sulfuric acid fromthe resulting sulfonic acid; D. Neutralizing the sulfonic acid withlithium, sodium, potassium or calcium hydroxide or oxide or mixturesthereof; E. Separating or centrifuging the neutral metal sulfonate fromany by-product metal sulfates; and F. Stripping the final product freeof any solvent and/or water.
 2. The method defined in claim 1 andfurther characterized as including a paraffinic volatile solventselected from the group consisting of hexane, isohexane, heptane,isoheptane, octane, isooctane and others with an IBP of 250° F. or less.3. The method of claim 2 wherein the amounts of solvent, oils, andalkylbenzene compounds are such that the admixture contains thefollowing amount of materials: Parts by Weight Heavy paraffinic oil 2-15Light Paraffinic oil 2-15 Linear monoalkylbenzene 5-18 UnbranchedDialkylbenzene 10-25  C-1 Methyl Branched Dialkylbenzene 2-10 VolatileSolvent 20-70 


4. The method of claim 2 wherein the solvent dewaxed heavy paraffinicoil or heavy lubricating oil has a viscosity index of at least 90, aninitial boiling point of at least 330° C. a viscosity of at least 100cSt at 40° C. and a Cleveland Open Cup flash point of at least 240° C.5. The method of claim 2 wherein the solvent dewaxed light paraffinicoil or light lubricating oil has a viscosity index of at least 90, aninitial boiling point of at least 320° F., a viscosity of at least 10cSt at 100° C. and a Cleveland Open Cup flash point of at least 210° C.6. The method of claim 2 wherein the linear monoalkylbenzene has alkylside chains of 10-14 carbon atoms, has a molecular weight of at least225 and a boiling point of at least 250° C.
 7. The method of claim 2wherein the unbranched dialkylbenzene has two alkyl side chains ofC₁₀-C₁₄ carbon side chains, has a molecular weight of at least 335 andan initial boiling point of at least 300° C.
 8. The method of claim 2wherein the C-1 methyl branched dialkylbenzene has two alkyl side chainscontaining C₁₀-C₁₃ alkyl groups, has a molecular weight of at least 375and an initial boiling point of at least 340° C.
 9. The method of claim2 wherein the solvent is selected from the group consisting of heptaneor naphtha.
 10. The method of claim 2 wherein the oleum used is selectedfrom 15 percent (15%) oleum to 25 percent (25%) oleum.
 11. The method ofclaim 2 wherein the oleum used is 20 percent (20%) and the mole ratio is1.2-1.4 moles of oleum per mole of sulfonatables.
 12. The method ofclaim 2 wherein the metal sulfonate is a sodium sulfonate having thefollowing composition and properties: Parts by Weight % Sodium sulfonate30-70 % Oil 30-70 Molecular weight 430-480 Viscosity, SUS @ 100° F.30-75 Specific gravity 0.94-0.99 Flash, COC ° F., minimum 350


13. The method of claim 2 wherein the metal sulfonate is a sodiumsulfonate prepared from 25 percent (25%) linear monoalkylbenzene, 41percent (41%) unbranched dialkylbenzene, 14 percent (14%) C-1 methylbranched dialkylbenzene, ten percent (10%) heavy paraffinic oil and tenpercent (10%) light paraffinic oil.
 14. The method of claim 2 whereinthe metal sulfonate is a sodium sulfonate prepared from 17 percent (17%)linear monoalkylbenzene, 31 percent (31%) unbranched dialkylbenzene, 12percent (12%) C-1 methyl branched dialkylbenzene, 20 percent (20%) heavyparaffinic oil and 20 percent (20%) light paraffinic oil.
 15. The methodof claim 2 wherein the metal sulfonate is a sodium sulfonate preparedfrom mixtures of products outlined in claims 13 and
 14. 16. The methodof claim 2 wherein the metal sulfonate is a lithium sulfonate preparedfrom the mixtures of products outlined in claims 13 and
 14. 17. Themethod of claim 2 wherein the metal sulfonate is a potassium sulfonateprepared from the mixtures of products outlined in claims 13 and
 14. 18.The method of claim 2 wherein the metal sulfonate is a calcium sulfonateprepared from the mixtures of products outlined in claims 13 and 14.